An adiabatic plug flow reactor (PFR) with recycle is used to carry out a first-order reaction. The fresh feed inlet temperature T_i and concentration are known, but the inlet temperature T₀ and the inlet concentration to the PFR are not. Since T₀ and the inlet concentration are initial conditions needed to solve the differential equations for the mass and energy balances for the PFR, an iterative solution is needed. The value of T₀ can be calculated only when the differential equations are solved for T_final. Thus, the value of T₀ is guessed using the slider (and the feed concentration to the reactor calculated using the adiabatic relation between temperature and concentration), and the exit temperature T_final from the PFR is then obtained from the solution of the differential equations. The estimated value of T₀ is adjusted until the calculated value of T_i (arrow in figure on left) equals the known T_i (the green circle); multiple solutions are possible under some conditions. High recycle ratios approach continuous-stirred tank reactor (CSTR) behavior. A plot of temperature as a function of distance down the PFR is generated. The inlet temperature to the system T_i and the recycle ratio can be varied.

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About:

This simulation was made at the University of Colorado Boulder, Department of Chemical and Biological Engineering.  Author: Rachael L. Baumann

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